Thanks Bernie,
I have the message: This is the WebDAV interface. It can only be accessed by WebDAV clients such as the Nextcloud desktop sync client.
So I guess service discovery is working, the fact that another app can sync contacts is good to know as well…
Unfortunatly for me your method (automatic configuration, USERNAME@example.xyz) does not work either… Still “Unable to verify account name or password” on macOS
On iOS I succeeded but without SSL… don’t know why
but your method concerns caldav, and I do not have the same issue with caldav, just carddav

@Nextcloud-User you solved it. I need 'Advanced Settings: and add the port number and cut up the url in two input boxes.
Here for reference a screenshot of my working input:
[43]
Thanx all in this thread who contributed!